“We have long been concerned about the nefarious role of private equity in our economy,” the delegates said in the letter. “The dire threat of Steward’s collapse appears to be a textbook example of the grave risks posed by a private equity takeover of the health care system.”

A spokesperson for Cerberus was not immediately available for comment.

Previously, Steward has blamed its financial challenges in part on the relatively low rates it receives for services to Medicaid patients. And even for patients with more lucrative commercial insurance, Steward has said, its hospitals still are paid less than others in the market.

The letter comes amid increasing struggles for Steward Health Care, which is facing numerous lawsuits over alleged nonpayment to vendors, closing hospitals in other states, and having difficulty making rent payments. As reported by the Boston Globe, executives have been in talks with Massachusetts state officials over possible solutions to their financial crisis, which have included options ranging from selling or closing some hospitals or services, to at times requests for state financial support.

The Dallas-based health system, which counts nine hospitals in Massachusetts and more than 30 nationally, has so far announced the closure of one facility, New England Sinai Hospital, a rehabilitation hospital in Stoughton. Additional closures have not been announced, and the company has insisted that none are imminent.

Still, financial challenges have created problems at facilities that remain. Supply shortages have been so pervasive that Mass General Brigham removed some of its doctors for a time from performing surgeries at some Steward hospitals. Since late January, the Department of Public Health has been doing daily monitoring at many Steward hospitals to check on staffing and service availability, monitoring they increased this week.

The note to Cerberus was signed by the entire all-Democratic, delegation, including US Senators Elizabeth Warren and Edward Markey, and US Representatives Richard Neal, James McGovern, Stephen Lynch, William Keating, Katherine Clark, Seth Moulton, Lori Trahan, Ayanna Pressley, and Jake Auchincloss. According to the delegation, the current financial precarity was created — if not magnified — by Cerberus’s actions.

Warren’s office in particular has targeted private equity firms in legislation she’s filed, including the Stop Wall Street Looting Act, which among other things would have made private equity firms jointly liable for all the debt incurred by the acquired entity. Warren has filed such legislation in 2018 and 2021, though it did not pass.

Named after the mythical three-headed dog guarding the gates of the underworld, Cebrerus became involved with Steward at its founding. As detailed by the letter, Cerberus invested $246 million through the purchase of Caritas Cristi Health Care in 2010, rechristened the system as Steward, and left CEO Dr. Ralph de la Torre in charge.

Six years later, Cerberus-owned Steward signed a $1.25 billion deal with Medical Properties Trust, in which Steward sold its hospital properties to MPT, locking Steward into a multiyear, multimillion dollar lease payment. The deal returned Cerberus’s initial investment, but the private equity firm still retained a controlling stake in the company.

In May 2020, Cerberus exited entirely, transferring its ownership stake to a group of Steward doctors in exchange for a note that would provide regular interest payments. Steward borrowed $335 million from MPT in January 2021 to buy the note.

“Over the six-year period, Steward took on over a billion dollars in liabilities — while Cerberus executives profited handsomely,” the letter states. “The net result of these transactions appears to be an unfolding tragedy. Cerberus and its private equity executives received $800 million in profits, while thousands of Massachusetts health care workers’ jobs are at risk and 10 communities in the Commonwealth face the potential closure of hospitals that are debt-ridden, unable to pay their bills, and teetering on the financial brink.”

The letter comes after the delegation sent a similar missive to de la Torre in late January, asking for a seat at the table as Steward discussed its plans with state officials, and wanting a briefing on the health system’s financial position and the status of its facilities in Massachusetts.

Lynch said his staff and others met with Steward executives and were informed that Steward’s intent was to exit the Massachusetts health market. Of the remaining eight hospitals that will exist after the rehab hospital’s closure, four — Nashoba Valley Medical Center, St. Elizabeth’s Medical Center, Holy Family Hospital, and Norwood Hospital — had to be transferred urgently.

Norwood Hospital has been temporarily closed since 2020 due to catastrophic flooding.

Lynch said at the root of the financial struggle was the for-profit structure of Steward.

“They have two missions — they have to satisfy the obligations they have to their private equity firm and shareholders to generate a profit,” he said in an interview. “And then they got another mission, to provide high quality health care. Sometimes those two missions are at odds. There is friction between them. That’s at the root of this. It’s their business model.”

Jessica Bartlett can be reached at jessica.bartlett@globe.com. Follow her @ByJessBartlett.